1. Field
Exemplary embodiments of the present invention relate to a semiconductor device, and more particularly, to a semiconductor device having air gaps and a method for fabricating the semiconductor device.
2. Description of the Related Art
Generally, a semiconductor device includes a plurality of first conductive structures and second conductive structures, wherein each of the second conductive structures is formed between adjacent first conductive structures and an insulation layer is disposed between the first conductive structures and the second conductive structure. For example, the first conductive structures include gates, bit lines, and metal lines. The second conductive structures include contact plugs, storage node contact plugs, bit line contact plugs, and vias.
As semiconductor devices are highly integrated, the gaps between the first conductive structures and the second conductive structures become narrower and narrower. The narrowing gaps between the first conductive structures and the second conductive structures increase parasitic capacitance. The increase in the parasitic capacitance makes semiconductor devices operate slowly and deteriorates refresh characteristics of the semiconductor devices.
The dielectric rate of an insulation layer may be decreased in order to reduce the parasitic capacitance. Generally, silicon oxide or silicon nitride is used to form an insulation layer in a semiconductor device. The dielectric rate of silicon oxide is approximately 4, and the dielectric rate of silicon nitride is approximately 7.
Since the silicon oxide and the silicon nitride still have high dielectric rates, there may be limitation in decreasing the parasitic capacitance by using the silicon oxide and silicon nitride. Recently, researchers are studying to develop materials having a relatively low dielectric rate, but their dielectric rates may be not sufficiently low.